US20250329990A1 - Laser element and electronic device - Google Patents

Laser element and electronic device

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Publication number
US20250329990A1
US20250329990A1 US18/849,940 US202218849940A US2025329990A1 US 20250329990 A1 US20250329990 A1 US 20250329990A1 US 202218849940 A US202218849940 A US 202218849940A US 2025329990 A1 US2025329990 A1 US 2025329990A1
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reflection layer
light
polarization splitting
wavelength
laser
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Gen Yonezawa
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Sony Group Corp
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Sony Group Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0602—Crystal lasers or glass lasers
    • H01S3/0612—Non-homogeneous structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0619—Coatings, e.g. AR, HR, passivation layer
    • H01S3/0621—Coatings on the end-faces, e.g. input/output surfaces of the laser light
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0627—Construction or shape of active medium the resonator being monolithic, e.g. microlaser
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094073—Non-polarized pump, e.g. depolarizing the pump light for Raman lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094084—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
    • H01S3/09415—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/113—Q-switching using intracavity saturable absorbers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1611—Solid materials characterised by an active (lasing) ion rare earth neodymium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1618—Solid materials characterised by an active (lasing) ion rare earth ytterbium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
    • H01S5/18361—Structure of the reflectors, e.g. hybrid mirrors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • H01S3/2383—Parallel arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4012—Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/42—Arrays of surface emitting lasers
    • H01S5/423—Arrays of surface emitting lasers having a vertical cavity

Definitions

  • the present disclosure relates to a laser element and an electronic device.
  • a laser technique is applied to various fields such as microfabrication, medical devices, or distance measurement.
  • Application of a short pulse laser technique in particular to a highly accurate machining technique or a highly efficient wavelength conversion technique is expected.
  • a Q switch solid state laser among these techniques can obtain high peak power that exceeds kilowatt (kW) with a relatively simple configuration, and therefore is used in a wide application field (see PTL 1).
  • the excitation light source of this type has higher thermal resistance than that of an Edge Emitting Laser (EEL), and has an upper limit (rollover point) of a light output.
  • EEL Edge Emitting Laser
  • MTTF Mean Time to Failure
  • PTL 1 discloses a structure obtained by combining the laminated semiconductor layers with a solid state laser medium for a Q switch.
  • a first resonator constituted by the laminated semiconductor layer that is the excitation light source, and the solid state laser medium, and a second resonator constituted by a solid state laser medium and a saturable absorber are adjacent, so that it is possible to excite the solid state laser medium with a high intensity in the first resonator.
  • the waveform of the Q switch light oscillated by an excitation light emitting source includes jitters, and, even when the waveform is multiplexed, it is not possible to improve total peak power.
  • an upper limit of a peak intensity of the Q switch light is determined due to a limit of an excitation light output for the above-described reason.
  • the present disclosure provides a laser element and an electronic device that can improve an excitation light output without generating heat and lowering an operational life.
  • a laser element that includes: a laminated semiconductor layer that includes a first reflection layer used for light of a first wavelength and an active layer that performs surface light emission at the first wavelength;
  • the laminated semiconductor layer may include a plurality of laminated semiconductor regions associated with the orthogonal polarized beams, and the polarization splitting element may individually resonate and multiplex a corresponding polarized beam between the first reflection layer and the second reflection layer for each of the plurality of laminated semiconductor regions.
  • the polarization splitting element may include a first surface that is in contact with a light emission surface of the laminated semiconductor layer, and a second surface that is disposed on an opposite side to the first surface and between the first reflection layer and the second reflection layer.
  • the orthogonal polarized beams may include orthogonal polarized beams of different wavelengths
  • the orthogonal polarized beams may include a Transverse Magnetic (TM) polarized beam and a Transverse Electric (TE) polarized beam, and
  • the polarization splitting element may multiplex the TE polarized beam with the TM polarized beam inside the polarization splitting element.
  • the polarization splitting element may include a laminated body obtained by alternately laminating a plurality of polarization splitting films and a plurality of reflection films with an interval spaced apart from each other,
  • the polarization splitting element may include a birefringent material for splitting the light emitted from the laminated semiconductor layer into the orthogonal polarized beams.
  • the laser element may include a laser medium that is disposed closer to the light emission surface side than the polarization splitting element, and resonates at a second wavelength different from the first wavelength.
  • the laser element may include: a third reflection layer that is disposed on a first end surface of the laser medium on a side of the polarization splitting element, and is used for light of the second wavelength; and
  • the third reflection layer may be disposed closer to the light emission surface side than the second reflection layer.
  • the third reflection layer may be disposed between the polarization splitting element and the second reflection layer.
  • the third reflection layer may be in contact with an end surface of the polarization splitting element.
  • the fourth reflection layer may be in contact with the second reflection layer or disposed closer to the light emission surface side than the second reflection layer.
  • the laser element may include a saturable absorber that is disposed closer to the light emission surface side than the laser medium.
  • the laser element may include: a third reflection layer that is disposed on an end surface of the laser medium on a side facing the polarization splitting element, and is used for light of the second wavelength; and
  • the third reflection layer may be disposed closer to the light emission surface side than the second reflection layer.
  • the second reflection layer may be disposed between the third reflection layer and the fourth reflection layer.
  • Each of the laminated semiconductor layer, the polarization splitting element, the laser medium, and the saturable absorber may be divided into a plurality of regions in association with a plurality of light emitting units that emit pulse laser light of the second wavelength disposed at a predetermined interval.
  • the present disclosure provides an electronic device that includes: a laser element; and
  • FIG. 1 is a schematic cross-sectional view of a laser element according to a first embodiment.
  • FIG. 2 is a schematic cross-sectional view of a laser element and a plan view seen from a light emission surface side according to a comparative example.
  • FIG. 3 is a diagram illustrating a relationship between a current of an excitation light source and a light output in the laser element in FIG. 2 .
  • FIG. 4 is a schematic cross-sectional view of the laser element according to a second embodiment.
  • FIG. 5 is a view schematically illustrating a manufacturing method for a polarization splitting element.
  • FIG. 6 A is a diagram illustrating an example where a TM polarized beam and a TE polarized beam are multiplexed at a substantially center in a thickness direction of the polarization splitting element.
  • FIG. 6 B is a diagram illustrating an example where the TM polarized beam and the TE polarized beam are multiplexed at a portion shifted from the center in the thickness direction of the polarization splitting element.
  • FIG. 7 is a schematic cross-sectional view of the laser element according to a third embodiment.
  • FIG. 8 is a diagram illustrating a design example of a polarization splitting film.
  • FIG. 9 is a schematic cross-sectional view of the laser element according to a fourth embodiment.
  • FIG. 10 is a schematic cross-sectional view of the laser element according to a fifth embodiment.
  • FIG. 11 is a schematic cross-sectional view of the laser element according to a sixth embodiment.
  • FIG. 12 is a schematic cross-sectional view of the laser element according to a seventh embodiment.
  • FIG. 13 is a schematic cross-sectional view of the laser element according to an eighth embodiment.
  • FIG. 14 is a schematic cross-sectional view illustrating respective layers of the laser element in FIG. 13 in more detail.
  • FIG. 15 is a plan view and a cross-sectional view illustrating a plurality of laser elements disposed in an array.
  • FIG. 16 A is a cross-sectional view of a laser amplification element according to the present disclosure.
  • FIG. 16 B is a perspective view of the laser amplification element according to the present disclosure.
  • FIG. 17 is a diagram illustrating an example of a schematic configuration of an endoscopic system.
  • FIG. 18 is a block diagram illustrating an example of a functional configuration of a camera and a CCU illustrated in FIG. 20 .
  • FIG. 19 is a diagram illustrating an example of a schematic configuration of a microsurgery system.
  • the laser element and the electronic device may include components and functions that are not illustrated or explained. The following description does not exclude components or functions that are not illustrated or described.
  • FIG. 1 is a schematic cross-sectional view of a laser element 1 according to the first embodiment.
  • the laser element 1 according to the first embodiment includes an excitation light source 2 that includes a first reflection layer R 1 and an active layer, a second reflection layer R 2 , and a polarization splitting element 10 .
  • the laser element 1 according to the first embodiment has an integrated laminated structure that can be made using a semiconductor process technique, and consequently has good mass productivity as well as stability of a laser output.
  • the excitation light source 2 is the laminated semiconductor layer.
  • the excitation light source 2 is referred to as the laminated semiconductor layer 2 below.
  • the laminated semiconductor layer 2 is one form of a surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser). What is different from the VCSEL is that the second reflection layer R 2 that is at least one of mirrors that constitute a resonator is provided outside the laminated semiconductor layer 2 that is a main body of the excitation light source 2 .
  • the second reflection layer R 2 is, for example, an external resonator mirror.
  • the laminated semiconductor layer 2 is also referred to as a Vertical External-Cavity Surface Emitting Laser (VECSEL).
  • VECSEL Vertical External-Cavity Surface Emitting Laser
  • the laminated semiconductor layer 2 includes the first reflection layer R 1 that is used for light of a first wavelength ⁇ 1 , and the active layer that performs surface light emission at the first wavelength ⁇ 1 . A detailed layer configuration of the laminated semiconductor layer 2 will be described later.
  • the second reflection layer R 2 is disposed closer to a light emission surface side than the laminated semiconductor layer 2 .
  • the first reflection layer R 1 and the second reflection layer R 2 constitute a first resonator 11 that resonates light of the first wavelength ⁇ 1 .
  • the polarization splitting element 10 is an element of a flat plate shape that is provided between the first resonator 11 and polarizes and splits light from the excitation light source 2 .
  • the polarization splitting element 10 multiplexes orthogonal polarized beams while uniquely determining a polarization direction. That is, the polarization splitting element 10 individually resonates and multiplexes between the first reflection layer R 1 and the second reflection layer R 2 each of the orthogonal polarized beams included in light emitted from the laminated semiconductor layer 2 that constitutes the excitation light source 2 .
  • the internal structure of the polarization splitting element 10 does not matter.
  • One specific example of the polarization splitting element 10 is a Polarizing Beam Splitter (PBS).
  • the inside of the polarization splitting element 10 is provided with a first optical member 13 that allows a first polarized beam to transmit and reflects a second polarized beam, and a second optical member 14 that reflects the second polarized beam such that the first polarized beam transmits through the first optical member 13 and performs a resonating operation between the first reflection layer R 1 and the second reflection layer R 2 , and the second polarized beam is reflected by the second optical member 14 and the first optical member 13 , and performs a resonating operation between the first reflection layer R 1 and the second reflection layer R 2 .
  • the polarization splitting element 10 includes a first surface that is in contact with the light emission surface of the laminated semiconductor layer 2 , and a second layer that is disposed on a side opposite to the first surface and between the first reflection layer and the second reflection layer.
  • FIG. 2 is a schematic cross-sectional view of a laser element 100 and a plan view seen from a light emission surface side according to a comparative example.
  • the laser element 100 in FIG. 2 employs a configuration where the excitation light source 2 constituted by the laminated semiconductor layer 2 , a solid state laser medium 3 for a Q switch, and a saturable absorber 4 are disposed in this order.
  • a uniform material layer 15 that does not control polarization may be disposed between the excitation light source 2 and the solid state laser medium 3 .
  • This material layer 15 may be, for example, a support substrate that supports the excitation light source 2 .
  • the laser element 100 in FIG. 2 includes the first resonator 11 that resonates at the first wavelength ⁇ 1 , and a second resonator 12 that resonates at the second wavelength ⁇ 2 .
  • the second resonator 12 is also referred to as a Q switch solid state laser resonator.
  • the solid state laser medium 3 in FIG. 2 is used for both of the first resonator 11 and the second resonator 12 .
  • the first resonator 11 performs a resonating operation between the excitation light source 2 and the solid state laser medium 3
  • the second resonator 12 performs a resonating operation between the solid state laser medium 3 and the saturable absorber 4 .
  • FIG. 2 illustrates an example where the shape of a light emission unit 20 is circular.
  • the excitation light source 2 in FIG. 2 includes the laminated semiconductor layer 2 , and therefore the volume of the active layer in the laminated semiconductor layer 2 is limited.
  • the excitation light source 2 in FIG. 2 has lower thermal conductivity than an edge emitting laser, the active layer has a smaller volume, and therefore a light output cannot be increased.
  • Increasing power of the excitation light source 2 to increase the light output raises a junction temperature, and substantially lowers the operational life of the laser element 1 .
  • FIG. 3 is a diagram illustrating a relationship between a current of the excitation light source 2 and a light output in the laser element 100 in FIG. 2 .
  • the first resonator 11 performs a resonating operation at random irrespectively of types of the polarized beams. Only light energy is transmitted from the first resonator 11 to the second resonator 12 without selecting specific polarization.
  • the laminated semiconductor layer 2 constituting the excitation light source 2 is divided into a plurality of laminated semiconductor regions in association with orthogonal polarized beams included in the light emitted from the excitation light source 2 .
  • the plurality of laminated semiconductor regions emit spontaneous emission light of unpolarized beams.
  • the polarization splitting element 10 individually resonates and multiplexes a corresponding polarized beam between the first reflection layer R 1 and the second reflection layer R 2 for each of the plurality of laminated semiconductor regions.
  • each of the two types of the polarized beams individually performs a resonating operation between the first reflection layer R 1 and the second reflection layer R 2 , so that the laser element 1 in FIG. 1 can substantially double the light output emitted from the polarization splitting element 10 compared to FIG. 2 .
  • That the light output emitted from the polarization splitting element 10 can be improved means that, even when the current to be flown to the excitation light source 2 is reduced compared to the laser element 100 in FIG. 2 , a high light output can be maintained, and the current to be flown to the excitation light source 2 can be reduced, so that it is possible to increase the operational life of the laser element 1 .
  • the laser element 1 in FIG. 1 can have a bonded integrated structure by the semiconductor process. Consequently, it is possible to improve mass productivity, multiplex excitation light from a plurality of laminated semiconductor regions and increase an excitation light output, and improve the Mean Time to Failure (MTTF) of the laser element 1 .
  • MTTF Mean Time to Failure
  • the orthogonal polarized beams included in the light emitted from the laminated semiconductor layer 2 are resonated and multiplexed between the first reflection layer R 1 and the second reflection layer R 2 , so that it is possible to increase the excitation light output without increasing the current to be flown to the excitation light source 2 .
  • the excitation light source 2 is, for example, a semiconductor laser.
  • the polarization splitting element 10 is laminated in the first resonator 11 that uses the semiconductor laser, and the polarized beams split in the polarization splitting element 10 are multiplexed, so that even the small laser element 1 can improve the excitation light output. Furthermore, even when the current to be flown to the excitation light source 2 is decreased, it is possible to maintain the high excitation light source, so that it is possible to achieve a longer operational life of the laser element 1 .
  • FIG. 4 is a schematic cross-sectional view of a laser element la according to the second embodiment.
  • the orthogonal polarized beams included in the light emitted from the laminated semiconductor layer 2 include a Transverse Magnetic (TM) polarized beam and a Transverse Electric (TE) polarized beam.
  • the polarization splitting element 10 individually resonates and multiplexes each of the TE polarized beam and the TM polarized beam between the first reflection layer R 1 and the second reflection layer R 2 .
  • the polarization splitting element 10 is considered as a polarization conversion element (PS converter).
  • the polarization conversion element can be manufactured by the same manufacturing method as that used generally for a liquid crystal projector.
  • the polarization conversion element for the liquid crystal projector includes an opening window that is disposed on an incidence surface, and a half-wave plate that is disposed on an emission surface.
  • the polarization conversion element according to the present embodiment does not need the opening window and the half-wave plate, and includes a polarization splitting film 16 on a multiplexing surface instead.
  • the polarization splitting element 10 employs a configuration where the polarization splitting film 16 and a reflection film 17 disposed in a direction inclined at 45 degrees with respect to the normal direction of a light incidence surface are alternately disposed along the light incidence surface.
  • the polarization splitting film 16 has the property that allows the TM polarized beam to transmit, and reflects the TE polarized beam.
  • the reflection film 17 has the property that reflects the TE polarized beam.
  • the polarization splitting film 16 and the reflection film 17 are adjacently disposed along the light incidence surface such that the TM polarized beam resonates between the first reflection layer R 1 and the second reflection layer R 2 along the normal direction of the end surface of the polarization splitting element 10 .
  • the TE polarized beam resonates between the first reflection layer R 1 and the second reflection layer R 2 while being reflected by the reflection film 17 and the polarization splitting film 16 .
  • the TE polarized beam is reflected by the reflection film 17 , and multiplexed with the TM polarized beam when further reflected by the polarization splitting film 16 . Consequently, it is possible to increase the excitation light output that is output from the polarization splitting film 16 .
  • the laser element la according to the second embodiment can multiplex the TM polarized beam and the TE polarized beam.
  • FIG. 5 is a view schematically illustrating a manufacturing method for the polarization splitting element 10 .
  • a first substrate 22 including the polarization splitting film 16 formed on the end surface of a base material layer 21 , and a second substrate 24 including the reflection film 17 formed on the end surface of a base material layer 23 are alternately laminated to form a laminated body 25 .
  • Materials of the base material layers 21 and 23 do not matter in particular, and need to be a material that does not have a polarization splitting function.
  • the laminated body 25 is cut at an inclination angle of 45 degrees with respect to the normal direction of a substrate surface as indicated by two-dot chain lines in FIG. 5 to make a plurality of polarization splitting elements 10 including a plurality of the laminated bodies 25 .
  • the optical axes of light to be multiplexed match. Even when a positional shift in a substrate surface direction occurs at a time of bonding, the polarization splitting elements 10 have robustness that does not cause shift of optical paths of the polarization splitting elements 10 to be made.
  • FIG. 6 A illustrates an example where the TM polarized beam and the TE polarized beam are multiplexed at a substantially center in a thickness direction of the polarization splitting element 10
  • FIG. 6 B is a diagram illustrating an example where the TM polarized beam and the TE polarized beam are multiplexed at a portion shifted from the center in the thickness direction of the polarization splitting element 10 .
  • the polarization splitting element 10 formed by alternately disposing along the light incidence surface the polarization splitting film 16 and the reflection film 17 disposed in the direction inclined at 45 degrees from the normal direction of the substrate surface, it is possible to multiplex inside the polarization splitting element 10 the TM polarized beam and the TE polarized beam included in excitation light, and increase an excitation light output.
  • FIG. 7 is a schematic cross-sectional view of a laser element 1 b according to the third embodiment.
  • the laser element 1 b in FIG. 7 differs from the laser elements 1 and la according to the first and second embodiments in the internal structure of the polarization splitting element 10 .
  • the polarization splitting element 10 includes the polarization splitting film 16 and a plurality of reflection films 17 a and 17 b .
  • the plurality of reflection films 1717 a and 17 b reflect the TE polarized beams of respectively different wavelengths.
  • the polarization splitting element 10 in FIG. 7 includes the polarization splitting film 16 , the first reflection film 17 a that reflects the TE polarized beam of the wavelength ⁇ 1 , and the second reflection film 17 b that reflects the TE polarized beam of the wavelength ⁇ 2 .
  • FIG. 8 is a diagram illustrating a design example of the polarization splitting film 16 , and the horizontal axis indicates a wavelength and the vertical axis indicates a transmittance.
  • FIG. 9 is a schematic cross-sectional view of a laser element 1 c according to the fourth embodiment. While the laser elements la and 1 b in FIGS. 4 and 7 include the polarization splitting element 10 formed by alternately disposing the polarization splitting film 16 and the reflection film 17 , the laser element 1 c in FIG. 9 includes the polarization splitting element 10 made of a birefringent material.
  • the birefringent material is a material that splits incident light into orthogonal polarized beams depending on a polarization state of the incident light.
  • the birefringent material typically splits the incident light into two polarized beams. One of the two polarized beams is referred to as normal light (ordinary light), and the other one is referred to as abnormal light.
  • FIG. 9 illustrates an example where the TM polarized beam is the normal light, and the TE polarized beam is the abnormal light among the two polarized beams split by the birefringent material.
  • the TM polarized beam performs a resonating operation between the first reflection layer R 1 and the second reflection layer R 2 along the normal direction of the substrate surface.
  • the TE polarized beam diagonally travels in the birefringent material, is multiplexed with the TM polarized beam, and performs the resonating operation between the first reflection layer R 1 and the second reflection layer R 2 .
  • birefringent material examples include rutile that is crystal of titanium dioxide (TiO 2 ), crystal of yttrium vanadate (YVO 4 ), crystal of lithium niobate (LiNbO 3 ), crystal, and the like. Note that a specific type of the birefringent material does not matter. A material having high workability such that the transmittance is high with respect to the wavelength of the excitation light emitted from the excitation light source 2 , and accuracy in a C axis direction is obtained.
  • the rutile crystal is a birefringent material that has high birefringence, and a transmitting light beam can be split into ordinary light and abnormal light.
  • a polarization state of the abnormal light is orthogonal to a polarization state of the ordinary light.
  • the polarization splitting element 10 is formed using the birefringent material, so that it is possible to simplify the internal structure of the polarization splitting element 10 , and simplify the manufacturing process, too.
  • the polarization splitting element 10 it is necessary to optimize the thickness of the polarization splitting element 10 and the birefringent material.
  • FIG. 10 is a schematic cross-sectional view of a laser element 1 d according to the fifth embodiment.
  • the laser element 1 d in FIG. 10 employs a configuration where the solid state laser medium 3 is provided to the laser elements 1 , 1 a, 1 b, and 1 c according to one of the first to fourth embodiments.
  • the solid state laser medium 3 in FIG. 10 is disposed closer to the light emission surface side than the polarization splitting element 10 .
  • the solid state laser medium 3 is disposed closer to the light emission surface side than the second reflection layer R 2 .
  • the solid state laser medium 3 resonates at the second wavelength ⁇ 2 different from the first wavelength ⁇ 1 .
  • the solid state laser medium 3 includes a third reflection layer R 3 that is disposed on a first end surface, and a fourth reflection layer R 4 that is disposed on a second end surface on a side opposite to the first end surface.
  • the third reflection layer R 3 and the fourth reflection layer R 4 reflect light of the second wavelength ⁇ 2 . Then, the light of the second wavelength ⁇ 2 is resonated between the third reflection layer R 3 and the fourth reflection layer R 4 .
  • the solid state laser medium 3 contains, for example, Yttrium Aluminum Garnet (YAG) crystal Yb:YAG doped with Ytterbium (Yb).
  • YAG Yttrium Aluminum Garnet
  • Yb Ytterbium
  • the solid state laser medium 3 is not limited to, for example, Yb:YAG, and for example, at least one material of Nd:YAG, Nd:YVO 4 , Nd:YLF, Nd:glass, Yb:YAG, Yb:YLF, Yb:FAP, Yb:SFAP, Yb:YVO, Yb:glass, Yb:KYW, Yb:BCBF, Yb:YCOB, Yb:GdCOB, and YB:YAB can be used.
  • the form is not limited to crystal, and does not prevent use of ceramic materials.
  • the solid state laser medium 3 may be the four-level system solid state laser medium 3 , or may be a quasi-three-level system solid laser 3 .
  • each crystal has a different appropriate excitation wavelength (first wavelength ⁇ 1 )
  • the solid state laser medium 3 is disposed closer to the light emission surface side than the polarization splitting element 10 , so that it is possible to convert the wavelength of emission light.
  • the laser element 1 d according to the fifth embodiment can be also formed by the semiconductor process, so that it is possible to improve mass productivity.
  • a laser element according to the sixth embodiment includes a saturable absorber provided closer to the light emission surface side than the solid state laser medium 3 .
  • FIG. 11 is a schematic cross-sectional view of a laser element 1 e according to the sixth embodiment.
  • the laser element 1 e in FIG. 11 employs a configuration where the solid state laser medium 3 and the saturable absorber 4 are provided to the laser elements 1 to 1 c according to one of the first to fourth embodiments.
  • the solid state laser medium 3 in FIG. 11 is disposed closer to the light emission surface side than the polarization splitting element 10
  • the saturable absorber 4 is disposed closer to the light emission surface side than the solid state laser medium 3 .
  • the solid state laser medium 3 and the saturable absorber 4 resonate at the second wavelength ⁇ 2 different from the first wavelength ⁇ 1 .
  • the end surface of the solid state laser medium 3 on a side facing the polarization splitting element 10 is provided with the third reflection layer R 3 used for the light of the second wavelength ⁇ 2 .
  • the light emission surface side of the saturable absorber 4 is provided with the fourth reflection layer R 4 used for the light of the second wavelength ⁇ 2 .
  • the third reflection layer R 3 and the fourth reflection layer R 4 reflect the light of the second wavelength ⁇ 2 . Then, the light of the second wavelength ⁇ 2 is resonated between the third reflection layer R 3 and the fourth reflection layer R 4 .
  • the saturable absorber 4 contains, for example, YAG (Cr:YAG) crystal doped with Cr (chromium).
  • the saturable absorber 4 is a material whose transmittance increases when the intensity of incident light exceeds a predetermined threshold.
  • the excitation light of the first wavelength ⁇ 1 from the first resonator 11 increases the transmittance of the saturable absorber 4 , and emits a laser pulse of the second wavelength ⁇ 2 .
  • This is referred to as a Q switch.
  • V:YAG can be also used. In this regard, other types of the saturable absorber 4 may be used.
  • an active Q switch element is not prevented from being used as the Q switch.
  • the solid state laser medium 3 and the saturable absorber 4 are disposed in order on the light emission surface side of the polarization splitting element 10 , so that it is possible to emit a Q switch pulse without a jitter using excitation light whose light output has been improved by being multiplexed by the polarization splitting element 10 .
  • a laser element according to the seventh embodiment shares the solid state laser medium 3 for the first resonator 11 and the second resonator 12 .
  • FIG. 12 is a schematic cross-sectional view of a laser element If according to the seventh embodiment.
  • the laser element lf in FIG. 12 includes the solid state laser medium 3 disposed on the light emission surface side of the polarization splitting element 10 .
  • the first reflection layer R 1 is disposed on an end surface on the side opposite to the light emission surface of the laminated semiconductor layer 2 that is the excitation light source 2 .
  • the third reflection layer R 3 is disposed between the polarization splitting element 10 and the solid state laser medium 3 .
  • the second reflection layer R 2 and the fourth reflection layer R 4 are disposed on the light emission surface side of the solid state laser medium 3 .
  • the laser element If in FIG. 12 includes the first resonator 11 and the second resonator 12 .
  • the first resonator 11 resonates the light of the first wavelength ⁇ 1 between the first reflection layer R 1 and the second reflection layer R 2 .
  • the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the third reflection layer R 3 and the fourth reflection layer R 4 .
  • the solid state laser medium 3 is shared between the first resonator 11 and the second resonator 12 .
  • a laser element according to the eighth embodiment includes the saturable absorber 4 disposed closer to the light emission surface than the solid state laser medium 3 in the laser element If according to the seventh embodiment.
  • FIG. 13 is a schematic cross-sectional view of a laser element 1 g according to the eighth embodiment.
  • the laser element 1 g in FIG. 13 employs a configuration where the solid state laser medium 3 and the saturable absorber 4 are disposed in order on the light emission surface side of the polarization splitting element 10 .
  • the laser element 1 g in FIG. 13 includes the first reflection layer R 1 to the fourth reflection layer R 4 .
  • the first reflection layer R 1 is disposed on the end surface on the side opposite to the light emission surface of the laminated semiconductor layer 2 that is the excitation light source 2 .
  • the second reflection layer R 2 is disposed between the solid state laser medium 3 and the saturable absorber 4 .
  • the third reflection layer R 3 is disposed between the polarization splitting element 10 and the laser element 1 g.
  • the fourth reflection layer R 4 is disposed on the light emission surface side of the saturable absorber 4 .
  • the laser element 1 g in FIG. 13 includes the first resonator 11 and the second resonator 12 .
  • the first resonator 11 resonates the light of the first wavelength ⁇ 1 between the first reflection layer R 1 and the second reflection layer R 2 .
  • the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the third reflection layer R 3 and the fourth reflection layer R 4 .
  • the solid state laser medium 3 is shared as the first resonator 11 and the second resonator 12 .
  • the laser element 1 g in FIG. 13 can emit the Q switch pulse laser light whose pulse width is small, whose laser peak power is high and that has no jitter using excitation light whose light output has been improved by being multiplexed by the polarization splitting element 10 .
  • FIG. 14 is a schematic cross-sectional view illustrating respective layers of the laser element 1 g in FIG. 13 in more detail.
  • the laminated semiconductor layer 2 that is the excitation light source 2 includes two laminated semiconductor regions. Hereinafter, these two laminated semiconductor regions will be referred to as a first laminated semiconductor region 2 a and a second laminated semiconductor region 2 b.
  • the TM polarized beam performs a resonating operation between the first laminated semiconductor region 2 a, the polarization splitting element 10 , and the solid state laser medium 3 . Furthermore, the TE polarized beam emitted from the second laminated semiconductor region 2 b and split by the polarization splitting element 10 is multiplexed with the TM polarized beam inside the polarization splitting element 10 .
  • the excitation light source 2 constituted by the laminated semiconductor layer 2 to be divided into the first laminated semiconductor region 2 a and the second laminated semiconductor region 2 b has a structure that a substrate 5 , an n-contact layer 33 , a fifth reflection layer R 5 , a clad layer 6 , an active layer 7 , a clad layer 8 , a pre-oxidation layer 31 , and the first reflection layer R 1 are laminated in order.
  • the laser element 1 g in FIG. 1 employs a configuration of a bottom emission type where the substrate 5 emits excitation light of a Continuous Wave (CW), yet may also employ a configuration of a top emission type where CW excitation light is emitted from a first reflection layer R 1 side.
  • CW Continuous Wave
  • the substrate 5 is, for example, an n-GaAs substrate 5 .
  • the n-GaAs substrate 5 absorbs a certain rate of the light of the first wavelength ⁇ 1 that is the excitation wavelength of the excitation light source 2 , and is desirably made as thin as possible.
  • the n-GaAs substrate 5 desirably has such a thickness that mechanical strength at a time of a bonding process to be described later can be maintained.
  • the active layer 7 performs surface light emission at the first wavelength ⁇ 1 .
  • the clad layers 6 and 8 are, for example, AlGaAs clad layers.
  • the first reflection layer R 1 reflects the light of the first wavelength ⁇ 1 .
  • the fifth reflection layer R 5 has a certain transmittance with respect to the light of the first wavelength ⁇ 1 .
  • Distributed Bragg Reflectors (DBRs) that enable electrical conduction are used for the first reflection layer R 1 and the fifth reflection layer R 5 .
  • the current is injected from the outside through the first reflection layer R 1 and the fifth reflection layer R 5 , recombination and light emission occur in a quantum well in the active layer 7 , and laser oscillation at the first wavelength ⁇ 1 is performed.
  • Part of a pre-oxidation layer (e.g., AlAs layer) 31 on a clad layer side of the first reflection layer R 1 is oxidized as a post-oxidation layer (e.g., Al 2 O 3 layer) 32
  • the fifth reflection layer R 5 is disposed on, for example, the n-GaAs substrate 5 .
  • the fifth reflection layer R 5 includes the multilayer reflection film 17 made of Al z1 Ga 1-z1 As/Al z2 Ga 1-z2 As (0 ⁇ z1 ⁇ z2 ⁇ 1) doped with an n-type dopant (e.g., silicon).
  • the fifth reflection layer R 5 is also referred to as an n-DBR.
  • the n-contact layer 33 is disposed between the fifth reflection layer R 5 and the n-GaAs substrate 5 .
  • the active layer 7 includes a multiple quantum well layer formed by laminating, for example, an Al x1 In y1 Ga 1-x1-y1 As layer and an Al x3 In y3 Ga 1-x3-y3 As layer.
  • the first reflection layer R 1 includes, for example, a multilayer reflection film made of Al z3 Ga 1-z3 As/Al z4 Ga 1-z4 As (0 ⁇ z3 ⁇ z4 ⁇ 1) doped with a p-type dopant (e.g., carbon)
  • the first reflection layer R 1 is also referred to as a p-DBR.
  • the semiconductor layers R 5 , 6 , 7 , 8 , and R 1 in the excitation light source 2 can be formed using a crystal growth method such as the Metal Organic Chemical Vapor Deposition (MOCVD) method or the Molecular Beam Epitaxy (MBE) method. Furthermore, it is possible to perform driving by current injection after a process such as mesa etching for element isolation, formation of an insulating film, deposition of an electrode film, and the like after crystal growth.
  • MOCVD Metal Organic Chemical Vapor Deposition
  • MBE Molecular Beam Epitaxy
  • the solid state laser medium 3 is bonded to the end surface on the side opposite to the fifth reflection layer R 5 of the n-GaAs substrate 5 of the excitation light source 2 .
  • the end surface on an excitation light source 2 side of the solid state laser medium 3 will be referred to as a first surface F 1
  • an end surface on a saturable absorber 4 side of the solid state laser medium 3 will be referred to as a second surface F 2 .
  • a laser pulse emission surface of the saturable absorber 4 will be referred to as a third surface F 3
  • an end surface on the solid state laser medium 3 side of the excitation light source 2 will be referred to as a fourth surface F 4 .
  • an end surface on the solid state laser medium 3 side of the saturable absorber 4 will be referred to as a fifth surface F 5 .
  • the fourth surface F 4 of the excitation light source 2 is bonded to the first surface F 1 of the solid state laser medium 3
  • the second surface F 2 of the solid state laser medium 3 is bonded to the fifth surface F 5 of the saturable absorber 4 .
  • the laser element 1 in FIG. 1 includes the first resonator 11 and the second resonator 12 .
  • the first resonator 11 resonates the light of the first wavelength ⁇ 1 between the first reflection layer R 1 in the excitation light source 2 and the second reflection layer R 2 in the solid state laser medium 3 .
  • the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the third reflection layer R 3 in the solid state laser medium 3 and the fourth reflection layer R 4 in the saturable absorber 4 .
  • the second resonator 12 is also referred to as the Q switch solid state laser resonator 12 .
  • the second reflection layer R 2 that is a highly reflective layer is provided in the solid state laser medium 3 such that the first resonator 11 can perform a stable resonating operation.
  • the normal excitation light source 2 includes a partial reflection mirror that is disposed at a position of the second reflection layer R 2 in FIG. 1 and emits the light of the first wavelength ⁇ 1 to the outside.
  • the second reflection layer R 2 is used as the highly reflective layer to use the second reflection layer R 2 to trap power of the excitation light of the first wavelength ⁇ 1 in the first resonator 11 .
  • the first resonator 11 As described above, inside the first resonator 11 including the excitation light source 2 and the solid state laser medium 3 , three reflection layers (the first reflection layer R 1 , the fifth reflection layer R 5 , and the second reflection layer R 2 ) are provided. Hence, the first resonator 11 has a coupled cavity structure.
  • the solid state laser medium 3 By trapping the power of the excitation light of the first wavelength ⁇ 1 in the first resonator 11 , the solid state laser medium 3 is excited. Consequently, Q switch laser pulse oscillation occurs in the second resonator 12 .
  • the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the third reflection layer R 3 in the solid state laser medium 3 and the fourth reflection layer R 4 in the saturable absorber 4 .
  • the third reflection layer R 3 is a highly reflective layer
  • the fourth reflection layer R 4 is a partially reflective layer.
  • the fourth reflection layer R 4 is provided on the end surface of the saturable absorber 4 in FIG. 1 , the fourth reflection layer R 4 may be disposed closer to an optical axis rear side than the saturable absorber 4 .
  • the optical axis rear is an emission direction of light on the optical axis. That is, the fourth reflection layer R 4 does not necessarily need to be provided inside or on the front surface of the saturable absorber 4 .
  • the fourth reflection layer R 4 is an output coupling mirror in the second resonator 12 .
  • FIG. 1 illustrates the separated excitation light source 2 , solid state laser medium 3 , and saturable absorber 4 are separated, these excitation light source 2 , solid state laser medium 3 , and saturable absorber 4 are a laminated structure that has been integrated by being bonded using the bonding process.
  • the bonding process surface activated bonding, atomic diffusion bonding, plasma activation bonding, and the like can be used. Alternatively, other bonding (adhering) processes can be used.
  • electrodes E 1 and E 2 for injecting the current to the first reflection layer R 1 and the fifth reflection layer R 5 are desirably disposed such that at least the front surface of the n-GaAs substrate 5 is not exposed.
  • the electrodes E 1 and E 2 are disposed on the end surface on a first reflection layer R 1 side of the excitation light source 2 .
  • the electrode E 1 is a p electrode, and conducts with the first reflection layer R 1 .
  • the electrode E 2 is an n electrode, and is formed by filling a conductive material 35 in an inner wall of a trench that reaches the n-contact layer 33 from the first reflection layer R 1 with an insulating film 34 interposed therebetween.
  • the laser element 1 in FIG. 1 has the laminated structure, so that it is easy to make the laminated structure, and then dice and singulate the laminated structure into a plurality of chips, or form a laser array obtained by disposing in the array the plurality of laser elements 1 on one substrate.
  • arithmetic mean roughness Ra of each front surface layer needs to be 1 nm degree or less, and is desirably 0.5 nm or less.
  • Chemical Mechanical Polishing (CMP) is used to provide these front surface layers having the arithmetic mean roughness.
  • a dielectric multilayer film may be disposed between the respective layers, and the respective layers may be bonded with the dielectric multilayer films interposed therebetween to avoid light loss at the interface between the respective layers.
  • a refractive index n of the GaAs substrate surface 5 that is a base substrate of the excitation light source 2 with respect to 940 nm in wavelength is 3.5, and is a high refractive index compared to YAG (n:1.8) and general dielectric multilayer film materials.
  • an anti-reflection film (an AR coating film or an anti-reflection coating film) that does not reflect the light of the first wavelength ⁇ 1 of the first resonator 11 is desirably disposed between the excitation light source 2 and the solid state laser medium 3 . Furthermore, the anti-reflection film (the AR coating film or the anti-reflection coating film) is also desirably disposed between the solid state laser medium 3 and the saturable absorber 4 .
  • other materials than SiO 2 can be used as the underlayer, and are not limited to the materials.
  • an anti-reflection film may be provided between SiO 2 that is the material of the underlayer and the base material layer.
  • the dielectric multilayer film includes a Short Wave Pass Filter (SWPF), a Long Wave Pass Filter (LWPF), a Band Pass Filter (BPF), an anti-reflection (AR:Anti-Reflection) protective film, and the like, and is a coating layer formed by alternately laminating a high refractive index material layer and a low refractive index material layer.
  • SWPF Short Wave Pass Filter
  • LWPF Long Wave Pass Filter
  • BPF Band Pass Filter
  • AR:Anti-Reflection anti-reflection
  • the dielectric multilayer film includes a Short Wave Pass Filter (SWPF), a Long Wave Pass Filter (LWPF), a Band Pass Filter (BPF), an anti-reflection (AR:Anti-Reflection) protective film, and the like, and is a coating layer formed by alternately laminating a high refractive index material layer and a low refractive index material layer.
  • Different types of dielectric multilayer films are desirably disposed as needed.
  • the characteristics of the dielectric multilayer film can be also arbitrarily selected, and, for example, the third reflection layer R 3 may be the short wave pass filter and the second reflection layer R 2 may be the long wave pass filter. Furthermore, by applying the long wave pass filter to the second reflection layer R 2 , it is possible to prevent intrusion of the first wavelength ⁇ 1 in the saturable absorber 4 and prevent an erroneous operation of the Q switch.
  • short wave pass means to allow the light of the first wavelength ⁇ 1 to transmit, and reflect the light of the second wavelength ⁇ 2 .
  • long wave pass means to reflect the light of the first wavelength ⁇ 1 , and allows the light of the second wavelength ⁇ 2 to transmit.
  • a diffraction grating may be provided inside the second resonator 12 to convert a polarization state of a laser pulse to be emitted from random polarization into linear polarization.
  • a material such as SiO 2 can be formed as a film, and polished as an interface for bonding at the photonic crystal structure or a fine groove portion of the diffraction grating.
  • the current is injected into the active layer 7 via the electrode of the excitation light source 2 to cause laser oscillation of the first wavelength ⁇ 1 in the first resonator 11 and excite the solid state laser medium 3 .
  • the saturable absorber 4 is bonded to the solid state laser medium 3 , spontaneous emission light from the solid state laser medium 3 is absorbed by the saturable absorber 4 at an initial stage of occurrence of the laser oscillation of the first wavelength ⁇ 1 , optical feedback from the fourth reflection layer R 4 on an emission surface side of the saturable absorber 4 does not occur, and Q switch laser oscillation does not occur.
  • the TM polarized beam is multiplexed with the TE polarized beam to obtain a light output inside the polarization splitting element 10 , so that it is possible to increase the light output emitted from the polarization splitting element 10 .
  • the first resonator 11 resonates the light of the first resonator ⁇ 1 between the first reflection layer R 1 that is disposed on the end surface on the side opposite to the light emission surfaces of the first laminated semiconductor region 2 a and the second laminated semiconductor region 2 b, and the second reflection layer R 2 between the solid state laser medium 3 and the saturable absorber 4 .
  • the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the third reflection layer R 3 between the polarization splitting element 10 and the solid state laser medium 3 , and the fourth reflection layer R 4 on the light emission surface side of the saturable absorber 4 .
  • the solid state laser medium 3 between the first resonator 11 and the second resonator 12 , it is possible to emit Q switch pulse laser light whose pulse width is small, whose laser peak power is high, and that has no jitter.
  • FIG. 15 is a plan view and a cross-sectional view illustrating a plurality of laser elements 1 h disposed in an array.
  • the laminated semiconductor layer 2 that constitutes the excitation light source 2 is divided into a plurality of the laminated semiconductor regions 2 a and 2 b.
  • One of the two adjacent laminated semiconductor regions 2 a and 2 b is used to emit the TM polarized beam, and the other one is used to multiplex the TE polarized beam with the TM polarized beam.
  • excitation light is emitted from one Mesa A of two light emission units corresponding to the two adjacent laminated semiconductor regions 2 a and 2 b
  • excitation light is hardly emitted from the other Mesa B.
  • the light emission unit that emits the excitation light may be made larger.
  • the plurality of laser elements 1 h whose light outputs have been increased by providing the polarization splitting element 10 are disposed in the two-dimensional direction, so that it is possible to implement the laser elements 1 h that can achieve a high light output and have a longer operational life.
  • FIG. 16 A is a cross-sectional view of a laser amplification element 50 according to the present disclosure
  • FIG. 16 B is a perspective view of the laser amplification element 50 according to the present disclosure
  • FIG. 16 C is a plan view schematically illustrating an optical path of laser light in the laser amplification element 50 .
  • the laser amplification element 50 in FIGS. 16 A to 16 C includes an excitation light source 53 that is disposed on a support substrate 51 with a submount substrate 52 interposed therebetween, a polarization splitting element 60 that is disposed on the excitation light source 53 , and a solid state laser medium 54 that is disposed on the polarization splitting element 60 , and is not provided with the saturable absorber 4 .
  • the solid state laser medium 54 is, for example, Yb:YAG.
  • the excitation light source 53 and the solid state laser medium 54 constitute a first resonator 55 , and the light of the first wavelength ⁇ 1 is resonated in an upper/lower direction (lamination direction) in FIG. 16 A .
  • the first resonator 55 resonates the light of the first wavelength ⁇ 1 between the first reflection layer R 1 (p-DBR 72 ) in the excitation light source 53 and the second reflection layer R 2 in the solid state laser medium 54 .
  • the solid state laser medium 3 in the laser element 1 in FIG. 1 includes the third reflection layer R 3 on the end surface facing the excitation light source 2 , and includes the fourth reflection layer R 4 on the end surface facing the saturable absorber 4
  • the solid state laser medium 54 in FIG. 16 A does not need the reflection layer on the end surface facing the excitation light source 53 , and includes the second reflection layer R 2 on the end surface on the side opposite to the reflection layer.
  • the laser amplification element 50 in FIGS. 16 A to 16 C includes the first reflection member 56 and the second reflection member 57 that are disposed along an opposing first side surface 54 S 1 and second side surface 54 S 2 of the solid state laser medium 54 , and the solid state laser medium 54 that functions as an amplification medium 83 that causes the light of the second wavelength ⁇ 2 to reciprocate a plurality of times between the first reflection member 56 and the second reflection member 57 .
  • the first reflection member 56 and the second reflection member 57 may include flat reflection mirrors, or may have reflection mirrors of convex shapes to increase the light intensity in a process of amplification and avoid optimal damages on the materials.
  • first reflection member 56 and the second reflection member 57 are disposed at a distance apart from the first side surface 54 S 1 and the second side surface 54 S 2 of the solid state laser medium 54 in FIG. 16 A , multilayer films formed by laminating at least one of a semiconductor material, a metal material, and a dielectric material on the first side surface 54 S 1 and the second side surface 54 S 2 may be formed, and these multilayer films may be used as the reflection mirrors.
  • the laser amplification element 50 in FIGS. 16 A to 16 C includes a light input unit IN that is provided along the first side surface 54 S 1 , and a light output unit OUT that is provided along the second side surface 54 S 2 .
  • the light input unit IN inputs weak light (seed light) of the second wavelength ⁇ 2 to the first side surface 54 S 1 .
  • the light of the second wavelength ⁇ 2 reciprocates a plurality of times in the amplification medium 83 , and is emitted from the light output unit OUT.
  • the laser amplification element 50 includes the polarization splitting element 60 similar to the polarization splitting element 10 according to the first to ninth embodiments. By providing the polarization splitting element 60 , it is possible to increase the light output emitted from the polarization splitting element 10 .
  • the laser amplification element 50 in FIGS. 16 A to 16 C may include a cooling member 62 .
  • the cooling member 62 is bonded to the side surfaces of the excitation light source 53 , the polarization splitting element 60 , and the solid state laser medium 54 , and dissipates heat generated by at least one of the excitation light source 53 , the polarization splitting element 60 , and the solid state laser medium 54 .
  • the cooling member 62 is, for example, a metal material such as Cu having higher thermal conductivity.
  • the cooling member 62 may be bonded to an unillustrated package, and dissipates heat from the cooling member 62 to the package.
  • the support substrate 51 of the laser amplification element 50 in FIGS. 16 A to 16 C is, for example, a Cu substrate, and the submount substrate 52 is disposed thereon.
  • the submount substrate 52 is, for example, a laminated structure of an SiC layer 64 and an AuSn layer 65 , and p electrodes 73 and n electrodes 74 of the excitation light source 53 are electrically insulated from each other and bonded on the AuSn layer 65 .
  • the excitation light source 53 is the laminated semiconductor layer 2 formed by laminating an n-contact layer 67 , an n-DBR 68 , a clad layer 69 , an active layer 70 , a clad layer 71 , and a p-DBR 72 in order on an n-GaAs substrate 66 .
  • the p electrodes 73 and the n electrodes 74 are alternately disposed on the p-DBR 72 .
  • the p electrodes 73 conduct with the p-DBR 72
  • the n electrodes 74 conduct with the n-DBR 68 via a via 75 .
  • the laser amplification element 50 includes the first resonator 55 similarly to FIG. 1 .
  • the first resonator 55 resonates the light of the first wavelength ⁇ 1 between the first reflection layer R 1 in the excitation light source 53 and the second reflection layer R 2 in the solid state laser medium 54 .
  • the first reflection layer R 1 is the p-DBR 72
  • the second reflection layer R 2 is disposed on, for example, the upper surface of a heat exhaust member 61 .
  • the heat exhaust member 61 may be omitted.
  • the resonating operation of the light of the first wavelength ⁇ 1 performed by the first resonator 55 excites the solid state laser medium 54 .
  • FIG. 16 A schematically illustrates the resonating operation of the first resonator 55 as a thin line.
  • Amplified light (seed light) of the second wavelength ⁇ 2 is caused to be incident on the solid state laser medium 54 in the excited state in a left direction from the right end in FIG. 16 A .
  • stimulated emission of the amplified light occurs, and the amplified light is subjected to laser amplification.
  • Yb:YAG is used as the amplification medium 83
  • laser light whose wavelength is 1030 nm is used as seed light
  • the laser light is absorbed in a region that is not excited in the amplification medium 83 , and cannot be sufficiently amplified.
  • seed light that does not cause light absorption even in a non-excited state and whose wavelength is 1050 nm can be used. In this case, light absorption may not occur even in the non-excited state, and therefore the wavelength of the seed light is not limited to 1050 nm.
  • the size of the solid state laser medium 54 in the laser amplification element 50 according to the present disclosure is not restricted by an absorption length of excitation light, so that it is possible to increase the area of the solid state laser medium 54 irrespectively of the absorption length of the excitation light. By increasing the area of the solid state laser medium 54 , it is possible to further improve an amplification factor of the laser amplification element 50 .
  • the excitation light source 53 constituted by the laminated semiconductor layer 2 and the solid state laser medium 54 can be integrally bonded, and the laser amplification element 50 according to the present disclosure can be manufactured by a general-purpose semiconductor process, so that it is easy to achieve miniaturization, and it is also possible to reduce manufacturing cost.
  • the technique according to the present disclosure is widely applicable to medical imaging systems (hereinafter, also referred to as electronic devices), distance measurement systems such as Light Detection And Ranging (LiDAR) devices, light sources for laser machining devices, and the like.
  • the medical imaging systems are medical systems that use an imaging technique, and are, for example, an endoscopic system and a microscopic system.
  • FIG. 17 is a diagram illustrating an example of a schematic configuration of an endoscopic system 5000 to which the technique according to the present disclosure is applicable.
  • FIG. 18 is a diagram illustrating an example of configurations of an endoscope 5001 and a Camera Control Unit (CCU) 5039 .
  • FIG. 17 illustrates a state where a surgeon (doctor) 5067 who is a surgery participant is performing a surgical operation on a patient 5071 on a patient bed 5069 by using the endoscopic system 5000 . As illustrated in FIG.
  • the endoscopic system 5000 includes the endoscope 5001 that is the medical imaging device, the CCU 5039 , a light source device 5043 , a recording device 5053 , an output device 5055 , and a support device 5027 that supports the endoscope 5001 .
  • an insertion auxiliary tool that is called a trocar 5025 is punctured to the patient 5071 . Furthermore, a scope 5003 and a surgical tool 5021 connected to the endoscope 5001 are inserted into a body of the patient 5071 via the trocar 5025 .
  • the surgical tool 5021 are an energy device such as an electrical scalpel and a forcep.
  • a surgical operation image that is a medical image showing the interior of the body of the patient 5071 imaged by the endoscope 5001 is displayed on a display device 5041 .
  • the surgeon 5067 treats a surgical operation target using the surgical tool 5021 while looking at the surgical operation image displayed on the display device 5041 .
  • the medical image is not limited to the surgical operation image, and may be a diagnosis image that is imaged during diagnosis.
  • the endoscope 5001 is an imaging unit that images the interior of the body of the patient 5071 , and is a camera 5005 that includes, for example, a condenser optical system 50051 that condenses incident light, a zoom optical system 50052 that changes a focal distance of the imaging unit and enables optical zoom, a focus optical system 50053 that changes the focal distance of the imaging unit and enables focus adjustment, and a light reception element 50054 as illustrated in FIG. 18 .
  • the endoscope 5001 generates a pixel signal by condensing the light on the light reception element 50054 via the connected scope 5003 , and outputs the pixel signal to the CCU 5039 via a transmission system.
  • the scope 5003 is an insertion part that includes an objective lens at the distal end, and guides light from the connected light source device 5043 to the interior of the body of the patient 5071 .
  • the scope 5003 is, for example, a rigid scope in a case of a rigid mirror, and a flexible scope in a case of a flexible mirror.
  • the scope 5003 may be a forward-viewing endoscope or a forward-oblique viewing endoscope.
  • the pixel signal may be a signal that is based on a signal output from a pixel, and is, for example, a RAW signal or an image signal.
  • a memory may be mounted on the transmission system that connects the endoscope 5001 and the CCU 5039 , and the memory may be configured to store parameters related to the endoscope 5001 and the CCU 5039 .
  • the memory may be disposed, for example, at a connection portion or on a cable of the transmission system.
  • the memory of the transmission system stores parameters at a time of shipping of the endoscope 5001 or parameters that change at a time of power distribution, and an operation of the endoscope may be changed based on the parameters read from the memory.
  • a set of the endoscope and the transmission system may be referred to as an endoscope.
  • the light reception element 50054 is a sensor that converts received light into a pixel signal, and is, for example, a Complementary Metal Oxide Semiconductor (CMOS) type imaging element.
  • CMOS Complementary Metal Oxide Semiconductor
  • the light reception element 50054 is preferably an imaging element that includes a Bayer layout and can perform color photographing.
  • the light reception element 50054 is preferably an imaging element that includes the number of pixels matching a resolution of 4K (the number of horizontal pixels: 3840 ⁇ the number of vertical pixels: 2160), 8K (the number of horizontal pixels: 7680 ⁇ the number of vertical pixels: 4320), or square 4K (the number of horizontal pixels: 3840 or more ⁇ the number of vertical pixels: 3840 or more).
  • the light reception element 50054 may be one sensor chip or may be a plurality of sensor chips.
  • a prism that splits incident light per predetermined wavelength band may be provided, and a different light reception element may be configured to image each wavelength band.
  • a plurality of light reception elements may be provided for stereoscopic vision.
  • the light reception element 50054 may be a sensor that includes an arithmetic processing circuit for image processing in a chip structure, and may be a Time of Flight (ToF) sensor.
  • the transmission system is, for example, an optical fiber cable or wireless transmission.
  • Wireless transmission only needs to enable transmission of a pixel signal generated by the endoscope 5001 , and, for example, the endoscope 5001 and the CCU 5039 may be wirelessly connected, or the endoscope 5001 and the CCU 5039 may be connected via a base station in an operating room.
  • the endoscope 5001 may simultaneously transmit not only the pixel signal, but also information (e.g., a processing priority of the pixel signal, a synchronization signal, or the like) related to the pixel signal.
  • information e.g., a processing priority of the pixel signal, a synchronization signal, or the like
  • the endoscope is integrated with the scope and the camera, and the light reception element is provided at a distal end part of the scope.
  • the CCU 5039 is a control device that integrally controls the connected endoscope 5001 or light source device 5043 , and is, for example, an information processing device that includes an FPGA 50391 , a CPU 50392 , a RAM 50393 , a ROM 50394 , a GPU 50395 , and an I/F 50396 as illustrated in FIG. 18 . Furthermore, the CCU 5039 may integrally control the connected display device 5041 , recording device 5053 , and output device 5055 . For example, the CCU 5039 controls an irradiation timing, an irradiation intensity, an irradiation light source type of the light source device 5043 .
  • the CCU 5039 performs image processing such as development processing (e.g., demosaic processing) or correction processing on a pixel signal output from the endoscope 5001 , and outputs the processed pixel signal (e.g., image) to an external device such as the display device 5041 . Furthermore, the CCU 5039 transmits a control signal to the endoscope 5001 , and controls driving of the endoscope 5001 .
  • the control signal is, for example, information related to imaging conditions such as a magnification and a focal distance of the imaging unit.
  • the CCU 5039 has an image down-conversion function, and may be configured to be able to simultaneously output a high-resolution (e.g., 4K) image to the display device 5041 , and a low-resolution (e.g., HD) image to the recording device 5053 .
  • a high-resolution e.g., 4K
  • a low-resolution e.g., HD
  • the CCU 5039 may be connected with an external device (e.g., a recording device, a display device, an output device, or a support device) via an IP converter that converts a signal into a predetermined communication protocol (e.g., Internet Protocol (IP)).
  • IP Internet Protocol
  • Connection of the IP converter and the external device may be configured by a wired network, or part or entirety of a network may be constructed as a wireless network.
  • the IP converter on a CCU 5039 side has a wireless communication function, and may transmit a received video to an IP switcher or an output side IP converter via a wireless communication network such as the fifth generation mobile communication system (5G) or the sixth generation mobile communication system (6G).
  • 5G fifth generation mobile communication system
  • 6G sixth generation mobile communication system
  • the light source device 5043 is a device that can radiate light of a predetermined wavelength band, and includes, for example, a plurality of light sources, and a light source optical system that guides light of the plurality of light sources.
  • the light source is, for example, a xenon lamp, a LED light source, or an LD light source.
  • the light source device 5043 includes LED light sources that are respectively associated with, for example, the three primary colors R, G, and B, and emit white light by controlling an output intensity or an output timing of each light source.
  • the light source device 5043 may include a light source that can radiate special light used for special light observation in addition to a light source that radiates normal light used for normal light observation.
  • the special light is light of a predetermined wavelength band different from the normal light that is light for normal light observation, and is, for example, near infrared light (light whose wavelength is 760 nm or more), infrared light, blue light, and ultraviolet light.
  • the normal light is, for example, white light or green light. According to narrow band light observation that is one type of special light observation, it is possible to image predetermined tissues such as blood vessels of a mucous surface layer with a high contrast using wavelength dependency of absorption of light in body tissues by alternately radiating blue light and green light.
  • fluorescence observation that is one type of special light observation
  • by radiating excitation light for exciting a drug injected into the body tissues, receiving fluorescence emitted from the drug that is the body tissues or a target, and obtaining a fluorescent image the surgeon can easily visually check the body tissues or the like that the surgeon has difficulty in visually checking using the normal light.
  • fluorescence observation that uses the infrared light
  • ICG IndoCyanine Green
  • a drug e.g., 5-ALA
  • a type of irradiation light is set to the light source device 5043 under control of the CCU 5039 .
  • the CCU 5039 may have a mode that normal light observation and special light observation are alternately performed by controlling the light source device 5043 and the endoscope 5001 .
  • information based on a pixel signal obtained by special light observation is preferably superimposed on a pixel signal obtained by normal light observation.
  • special light observation may be infrared light observation for radiating infrared light and observing the depth beyond an organ front surface, or multispectral observation that utilizes hyperspectral spectroscopy.
  • photodynamic therapy may be used in combination.
  • the recording device 5053 is a device that records a pixel signal (e.g., image) acquired from the CCU 5039 , and is, for example, a recorder.
  • the recording device 5053 records in an HDD, an SDD, or an optical disk the image acquired from the CCU 5039 .
  • the recording device 5053 may be connected to a network in a hospital, and made accessible from a device outside an operating room. Furthermore, the recording device 5053 may have an image down-conversion function or up-conversion function.
  • the display device 5041 is, for example, a device that can display images, and is, for example, a display monitor.
  • the display device 5041 displays a display image based on the pixel signal acquired from the CCU 5039 .
  • the display device 5041 includes a camera and a microphone to function as an input device that enables visual line recognition, voice recognition, and instruction input using a gesture.
  • the output device 5055 is a device that outputs information acquired from the CCU 5039 , and is, for example, a printer.
  • the output device 5055 prints on paper a print image based on the pixel signal acquired from the CCU 5039 .
  • the support device 5027 is an articulated arm that includes a base part 5029 including an arm control device 5045 , an arm part 5031 that extends from the base part 5029 , and a holding part 5032 that is attached to the distal end of the arm part 5031 .
  • the arm control device 5045 includes a processor such as a CPU, and controls driving of the arm part 5031 by operating according to a predetermined program.
  • the support device 5027 controls parameters such as the length of each link 5035 that constitutes the arm part 5031 and a rotation angle and a torque of each joint 5033 using the arm control device 5045 to control, for example, a position and a posture of the endoscope 5001 held by the holding part 5032 .
  • the support device 5027 functions an endoscope support arm that supports the endoscope 5001 during a surgical operation. Consequently, the support device 5027 can play a role of a scopist who is an assistant holding the endoscope 5001 .
  • the support device 5027 may be a device that supports a microscope apparatus 5301 to be described later, and can be also referred to as a medical support arm.
  • control of the support device 5027 may be an autonomous control scheme that uses the arm control device 5045 , or may be a control scheme that is controlled by the arm control device 5045 based on a user's input.
  • control scheme may be a master/slave scheme that controls the support device 5027 that is a slave device (replica device) that is a patient cart based on a motion of a master device (primary device) that is a surgeon console at the hand of the user.
  • control of the support device 5027 may be able to be remotely controlled from the outside the operating room.
  • FIG. 19 is a diagram illustrating an example of a schematic configuration of a microsurgery system to which the technique according to the present disclosure is applicable. Note that, in the following description, the same components as those of the endoscopic system 5000 will be denoted by the same reference numerals and detailed description thereof will be omitted.
  • FIG. 19 schematically illustrates a state where the surgeon 5067 performs a surgical operation on the patient 5071 on the patient bed 5069 by using the microsurgery system 5300 .
  • the microscope apparatus 5301 in place of the endoscope 5001 is simplified and illustrated.
  • the microscope apparatus 5301 in the description may indicate a microscope unit 5303 provided at the distal end of the link 5035 , or may indicate the entire configuration including the microscope unit 5303 and the support device 5027 .
  • an image of a surgical part imaged by the microscope apparatus 5301 is displayed as an enlarged image on the display device 5041 installed in the operating room.
  • the display device 5041 is installed to face the surgeon 5067 .
  • the surgeon 5067 performs various operations such as a resection of an affected part on the surgical part while observing a state of the surgical part through a video shown on the display device 5041 .
  • the microsurgery system is used for, for example, eye surgery and brain surgery.
  • the support device 5027 can also support another observation device or another surgical tool instead of the endoscope 5001 or the microscope unit 5303 at the distal end.
  • the other observation device may be, for example, forceps, tweezers, a pneumoperitoneum tube for pneumoperitoneum, or an energy treatment instrument for incising tissues and sealing a blood vessel by cauterization.
  • the observation device and the surgical tools are supported by the support device, so that the positions can be fixed with higher stability and the workload of the medical staff can be lighter than in manual support by the medical staff.
  • the technique according to the present disclosure may be applied to such a support device that supports configurations other than a microscope unit.
  • the technique according to the present disclosure can be suitably applied to the surgical tool 5021 in the configuration described above. More specifically, by irradiating an affected part of a patient with a laser pulse of a short pulse from the laser element 1 according to the present embodiment, it is possible to more safely and reliably treat the affected part.
  • the present technique can also take on the following configurations.
  • a laser element includes:
  • a second reflection layer that is disposed closer to a light emission surface side than the laminated semiconductor layer, and is used for the light of the first wavelength
  • the laminated semiconductor layer includes a plurality of laminated semiconductor regions associated with the orthogonal polarized beams, and the polarization splitting element individually resonates and multiplexes a corresponding polarized beam between the first reflection layer and the second reflection layer for each of the plurality of laminated semiconductor regions.
  • the polarization splitting element includes a first surface that is in contact with a light emission surface of the laminated semiconductor layer, and a second surface that is disposed on an opposite side to the first surface and between the first reflection layer and the second reflection layer.
  • the orthogonal polarized beams include orthogonal polarized beams of different wavelengths
  • the polarization splitting element individually resonates and multiplexes each of the orthogonal polarized beams including the orthogonal polarized beams of the different wavelengths between the first reflection layer and the second reflection layer.
  • the orthogonal polarized beams include a Transverse Magnetic (TM) polarized beam and a Transverse Electric (TE) polarized beam, and
  • the polarization splitting element multiplexes the TE polarized beam with the TM polarized beam inside the polarization splitting element.
  • the polarization splitting element includes a laminated body obtained by alternately laminating a plurality of polarization splitting films and a plurality of reflection films with an interval spaced apart from each other,
  • the polarization splitting element includes a birefringent material for splitting the light emitted from the laminated semiconductor layer into the orthogonal polarized beams.
  • the laser element described in any one of (1) to (8) further includes a laser medium that is disposed closer to the light emission surface side than the polarization splitting element, and resonates at a second wavelength different from the first wavelength.
  • the laser element described in (9) includes:
  • the third reflection layer is disposed closer to the light emission surface side than the second reflection layer.
  • the third reflection layer is disposed between the polarization splitting element and the second reflection layer.
  • the third reflection layer is in contact with an end surface of the polarization splitting element.
  • the fourth reflection layer is in contact with the second reflection layer or disposed closer to the light emission surface side than the second reflection layer.
  • the laser element described in (9) further includes a saturable absorber that is disposed closer to the light emission surface side than the laser medium.
  • the laser element described in (15) further includes:
  • the third reflection layer is disposed closer to the light emission surface side than the second reflection layer.
  • the second reflection layer is disposed between the third reflection layer and the fourth reflection layer.
  • each of the laminated semiconductor layer, the polarization splitting element, the laser medium, and the saturable absorber is divided into a plurality of regions in association with a plurality of light emitting units that emit pulse laser light of the second wavelength disposed at a predetermined interval.
  • An imaging device includes:

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